Chapter 22
Contaminants of Concern in Cannabis:
Microbes, Heavy Metals and Pesticides
John M. McPartland and Kevin J. McKernan
Abstract Microbiological contaminants pose a potential threat to cannabis con-
sumers. Bacteria and fungi may cause opportunistic infections in immunocom-
promized individuals. Even dead organisms may trigger allergies and asthma.
Toxins from microbial overloads, such as Shigla toxin and aflatoxins, may pose a
problem—unlikely, but possible. TheCannabisplant hosts a robust microbiome;
the identification of these organisms is underway.Cannabisbioaccumulates heavy
metals in its tissues, so avidly that hemp crops have been used for bioremediation.
Heavy metals cause myriad human diseases, so their presence in crops destined for
human consumption must be minimized. Pesticide residues in cannabis pose a
unique situation among crop plants—the Environmental Protection Agency
(EPA) will not propose pesticides guidelines, becauseCannabisis illegal on the
federal level. The use of illegal pesticides is a rising crisis, and a breakdown in
ethics. Testing for pesticide residues and maximal limits are proposed.
22.1 Introduction
Cannabis(the plant) and cannabis (the plant product) may be contaminated by
microbes, heavy metals, or pesticide residues. Thefirst two contaminants, microbes
and heavy metals, present a Janus-face or“flip-side of the coin”in relation to
Cannabis. Some bacteria and fungi are part of the plant’s microbiome. They pro-
vide benefits toCannabis. See the book chapter by Parijat Kusari and Oliver Kayser
for more about theCannabismicrobiome. On the“flip-side of the coin,”other
bacteria and fungi cause disease, and these must be controlled.
J.M. McPartland (&)
GW Pharmaceuticals place, 1 Cavendish Place, London W1G 0QF, UK
e-mail: [email protected]
K.J. McKernan
Courtagen Life Sciences, 12 Gill Street Suite 3700, Woburn, MA 01801, USA
©Springer International Publishing AG 2017
S. Chandra et al. (eds.), Cannabis sativaL. - Botany and Biotechnology,
DOI 10.1007/978-3-319-54564-6_22
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